注射成型聚合物充模取向应力场模型化理论研究:考虑熔体的可压缩性

Study on the Polymer Melt Flow-induced Orientation Stress Model in Injection Molding:With the Isothermal Compressible Hypothesis

研究复杂流场条件下恒温可压缩聚合物熔体注射充模流动取向应力场数学模型理论。针对缠结大分子链单体在成型充模过程中的无规形变特性,基于简化与假设,建立以缠结大分子链单体等效末端距矢量(End-to-end vector,ETEV)为核心的恒温可压缩聚合物充模取向物理模型;基于不可逆热力学与统计力学理论,推导得出大分子链单体流动取向应力形变模型;引入自由体积理论,阐明微元变形前后当量体积比率J与微元Finger应变张量-1C之关联性,进而得出恒温可压缩聚合物充模取向应力-应变'伪高弹'模型;研究聚合物微元的取向拉伸比λ与形变历史的相关性,得出非线性取向应力-形变关系模型,进而得出与经典K-BKZ模型具有一致形式的'伪高弹'积分模型;研究相关模型的物理性态,结果表面相关模型对表征相关聚合物充模取向工程问题具有较好的适配性与科学性。

The objective is to develop theoretical flow-induced orientation stress-strain relationship models for entangled polymer melt during injection molding process with the isothermal compressible hypothesis.In view of the trackless deformation characteristics of polymer entanglement macromolecular chain,the end-to-end distance vector（ETEV） is used to describe the evolution of the macromolecular chain morphology during the filling stage based on some reasonable simplified hypothesis,as the core of the flow-induced deformation physical model.Coupled with the irreversible thermodynamics and statistical mechanics theory,the flow-induced orientation stress-strain model of the molecular chain monomer is conducted.The relationship between equivalent volume ratio（J） and Finger strain tensor C-1 is also derived,and the corresponding pseudo-high-elastic mathematical model of entangled polymer melt is calculated.The correlation between the micro orientation stretching ratio λ and the deformation history is further elucidated,then the nonlinear orientation stress-strain model is deduced.And the pseudo-high-elastic integral model similar with the classic K-BKZ model is obtained.The structure feature and curve tendency of instantaneous model is demonstrated.Results indicate that the theoretical model is reliable and scientific for description the orientation problem.